SHIP2 and SHIP1 are constitutively tyrosine phosphorylated in primary human CP CML progenitor cells. Lysates of primitive blasts were subjected to immunoprecipitation with the indicated antibodies. After blotting with 4G10, the blot was stripped and reprobed sequentially with anti-SHIP1, anti-SHIP2, and anti-SHC antibodies. IgG refers to Ig heavy chain. A representative experiment is shown.